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21.
Point and area inventories of anthropogenic mercury emissions documented by US and Canadian environmental agencies have been aggregated into a single archive for analysis and air pollution modeling work. For 5341 point sources and 1634 aggregated area sources, mercury emissions are apportioned among elemental gaseous [Hg(0)], reactive gaseous[Hg(II)], and particulate [Hg(p)] emissions using speciation factors derived from available monitoring measurements. According to this inventory, 4.82 x 10(5) mol of mercury were emitted in calendar year 1996 in the latitude range 24-51 degrees north, and longitude range 64-91 degrees west, which covers most of North America east of the Mississippi River. Using speciation factors consistent with past emission source studies, we find the relative emission proportions among Hg(0):Hg(II):Hg(p) species are 47:35:18. Maps of the various mercury species' emissions patterns are presented. Gridded emission patterns show local mercury emission extremes associated with individual cement production and municipal incineration facilities, and in contrast to past inventories, population centers do not stand out. Considerable uncertainties are still present in estimating emissions from large point sources, as are methods of apportioning emissions among various mercury species. 相似文献
22.
Lemieux PM Gullett BK Lutes CC Winterrowd CK Winters DL 《Journal of the Air & Waste Management Association (1995)》2003,53(5):523-531
The uncontrolled burning of household waste in barrels has recently been implicated as a major source of airborne emissions of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). A detailed, systematic study to understand the variables affecting emissions of PCDD/Fs from burn barrels was performed. The waste composition, fullness of the barrel, and the combustion conditions within the barrel all contribute significantly to determining the emissions of PCDD/Fs from burn barrels. The study found no statistically significant effect on emissions from the Cl content of waste except at high levels, which are not representative of typical household waste. At these elevated Cl concentrations, the impact of Cl on PCDD/F emissions was found to be independent of the form of the Cl (inorganic or organic). For typical burn conditions, most of the PCDD/F emissions appear to be associated with the later stages of the burn when the waste is smoldering. Polychlorinated biphenyls (PCBs) were also measured for a subset of the tests. For the nominal waste composition, the average emissions were 76.8 ng toxic equivalency units (TEQ)WHO98/kg of waste combusted, which suggests that uncontrolled burning of household waste could be a major source of airborne PCDD/Fs in the United States. 相似文献
23.
LaRosa LE Buckley TJ Wallace LA 《Journal of the Air & Waste Management Association (1995)》2002,52(1):41-49
Black carbon (BC) was measured every 5 min for two years (May 1998-May 2000) inside and immediately outside a northern Virginia house (suburban Washington, DC) occupied by two nonsmokers. Two aethalometers, which measure BC by optical transmission through a quartz fiber tape, were employed indoors and outdoors. Meteorological parameters were obtained on an hourly basis from nearby Dulles airport. Indoor activities were recorded to identify indoor sources such as combustion activities, which occurred 9% of the time during the first year and 4% of the time during the second year. At times without indoor sources, indoor/outdoor BC ratios averaged 0.53 in the first year and 0.35 in the second year. The main outdoor source of BC was the general regional background, contributing 83-84% of the total during each of the two years. Morning rush hour traffic contributed 8-9% of the total BC. An evening peak in the fall and winter, thought to include contributions from wood burning, was responsible for approximately 8% of the annual average BC concentration. The main indoor sources of BC were cooking and candle burning, contributing 16 and 31%, respectively, of the annual average indoor concentrations in the two years. Relative humidity (RH) affected the outdoor aethalometer in both years. An artifact associated with the tape advance was noted for the aethalometer, but a correction factor was developed that reduced the associated error by a factor of 2. 相似文献
24.
Teuschler LK Gennings C Hartley WR Carter H Thiyagarajah A Schoeny R Cubbison C 《Chemosphere》2005,58(9):1283-1291
The United States Environmental Protection Agency (USEPA) has pursued the estimation of risk of adverse health effects from exposure to chemical mixtures since the early 1980s. Methods used to calculate risk estimates of mixtures were often based on single chemical information that required assumptions of dose-addition or response-addition and did not consider possible changes in response due to interaction effects among chemicals. Full factorial designs for laboratory studies can produce interactions information, but these are expensive to perform and may not provide the information needed to evaluate specific environmentally relevant mixtures. In this research, groups of Japanese medaka (Oryzias latipes) embryos were exposed to binary mixtures of benzene and toluene as well as to each of these chemicals alone. Endpoint specific dose-response models were built for the hydrocarbon mixture under an assumption of dose-additivity, using the single chemical dose-response information on benzene and toluene. The endpoints included heart rate, heart rate progression, and lethality. Results included a synergistic response for heart rate at 72 h of development, and either additivity or antagonism for all other endpoints at 96 h of development. This work uses an established statistical method to evaluate the toxicity of an environmentally relevant mixture to ascertain whether interaction effects are occurring, thus providing additional information on toxicity. 相似文献
25.
Jonathan M. H. Green Gemma R. Cranston William J. Sutherland Hannah R. Tranter Sarah J. Bell Tim G. Benton Eva Blixt Colm Bowe Sarah Broadley Andrew Brown Chris Brown Neil Burns David Butler Hannah Collins Helen Crowley Justin DeKoszmovszky Les G. Firbank Brett Fulford Toby A. Gardner Rosemary S. Hails Sharla Halvorson Michael Jack Ben Kerrison Lenny S. C. Koh Steven C. Lang Emily J. McKenzie Pablo Monsivais Timothy O’Riordan Jeremy Osborn Stephen Oswald Emma Price Thomas David Raffaelli Belinda Reyers Jagjit S. Srai Bernardo B. N. Strassburg David Webster Ruth Welters Gail Whiteman James Wilsdon Bhaskar Vira 《Sustainability Science》2017,12(2):319-331
Delivering access to sufficient food, energy and water resources to ensure human wellbeing is a major concern for governments worldwide. However, it is crucial to account for the ‘nexus’ of interactions between these natural resources and the consequent implications for human wellbeing. The private sector has a critical role in driving positive change towards more sustainable nexus management and could reap considerable benefits from collaboration with researchers to devise solutions to some of the foremost sustainability challenges of today. Yet opportunities are missed because the private sector is rarely involved in the formulation of deliverable research priorities. We convened senior research scientists and influential business leaders to collaboratively identify the top forty questions that, if answered, would best help companies understand and manage their food-energy-water-environment nexus dependencies and impacts. Codification of the top order nexus themes highlighted research priorities around development of pragmatic yet credible tools that allow businesses to incorporate nexus interactions into their decision-making; demonstration of the business case for more sustainable nexus management; identification of the most effective levers for behaviour change; and understanding incentives or circumstances that allow individuals and businesses to take a leadership stance. Greater investment in the complex but productive relations between the private sector and research community will create deeper and more meaningful collaboration and cooperation. 相似文献
26.
Petra Lasch Chris Kollas Joachim Rock Felicitas Suckow 《Regional Environmental Change》2010,10(2):83-94
Woody biomass generated in short-rotation coppice (SRC) plantations with aspen (Populus tremula L.) has good properties for bioenergy crop production: annual yields are high, labour input per year is low, and it is ecologically
valuable because of the multi-year rotation periods. Eastern Germany has a special advantage in producing bioenergy crops:
the former “agricultural cooperatives” built up quite large farms with, compared to Western Germany, comparatively large fields.
Therefore, a modelling study of the potential and the impacts of aspen SRC plantations in the five eastern federal states
of Germany under the recent climate and future climate projections was conducted. The ecophysiological forest growth model
4C was used to simulate the growth of aspen SRC plantations and their impacts on carbon in soils, and groundwater recharge,
on selected suitable areas currently under crops but with marginal site conditions for cropping. A clear signal to enhanced
growth condition over the whole area can be seen in the simulation of the mean annual woody biomass yield under conditions
of climate change, which increased from 7.47 t DW ha−1 a−1 under the recent climate to 9.26 t DW ha−1 a−1 at the end of the considered future period 2034–2055 under climate change. The mean soil carbon sequestration rate was 0.81 t C ha−1 a−1 under the recent climate and could rise up to 0.93 t C ha−1 a−1 under the assumption of climate change. On the other hand, the mean annual percolation rate, used as an indicator of impacts
on the regional water budget, will diminish under future climatic conditions. The results suggest that aspen SRC plantations
are a suitable contribution to regional CO2 mitigation and carbon sequestration under possible change of climate, but that negative impacts on the regional water budget
are possible. 相似文献
27.
Understanding the fate and transport of petroleum hydrocarbons from coal tar within gasholders 总被引:1,自引:0,他引:1
Coal tars have been identified as posing a threat to human health due to their toxic, mutagenic and carcinogenic characteristics. Workers involved in former gasholders decommissioning are potentially exposed to relevant concentrations of volatile and semi-volatile hydrocarbons upon opening up derelict tanks and during tar excavation/removal. While information on contaminated sites air-quality and its implications on medium-long term exposure is available, acute exposure issues associated with the execution of critical tasks are less understood. Calculations indicated that the concentration of a given contaminant in the gasholder vapour phase only depends on the coal tar composition, being only barely affected by the presence of water in the gasholder and the tar volume/void space ratio. Fugacity modelling suggested that risk-critical compounds such as benzene, naphthalene and other monocyclic and polycyclic aromatic hydrocarbons may gather in the gasholder air phase at significant concentrations. Gasholder emissions were measured on-site and compared with the workplace exposure limits (WELs) currently in use in UK. While levels for most of the toxic compounds were far lower than WELs, benzene air-concentrations where found to be above the accepted threshold. In addition due to the long exposure periods involved in gasholder decommissioning and the significant contribution given by naphthalene to the total coal tar vapour concentration, the adoption of a WEL for naphthalene may need to be considered to support operators in preventing human health risk at the workplace. The Level I fugacity approach used in this study demonstrated its suitability for applications to sealed environments such as gasholders and its further refining could provide a useful tool for land remediation risk assessors. 相似文献
28.
David C. Snyder Andrew P. Rutter Chris Worley Mike Olson Anthony Plourde Rebecca C. Bader Timothy Dallmann James J. Schauer 《Atmospheric environment (Oxford, England : 1994)》2010,44(13):1597-1608
Semi-continuous and 24-h averaged measurements of fine carbonaceous aerosols were made concurrently at three sites within each of two U.S. Midwestern Cities; Detroit, Michigan and Cleveland, Ohio; during two, one-month intensive campaigns conducted in July of 2007 and January & February of 2008. A comparison of 24-h measurements revealed substantial intra-urban variability in carbonaceous aerosols consistent with the influence of local sources, and excesses in both PM2.5 organic carbon (OC) and elemental carbon (EC) were identified at individual sites within each city. High time-resolved black carbon (BC) measurements indicated that elemental carbon concentrations were higher at sites adjacent to freeways and busy surface streets, and temporal patterns suggested that excess EC at sites adjacent to freeways was dominated by mobile source emissions while excesses in EC away from traffic corridors was dominated by point/area source emissions. The site-to-site variability in OC concentrations was approximately 7% within the neighborhood scale (0.5–4 km) and between 4 and 27% at the urban scale (4–100 km). In contrast, measurements of organic source tracers, in conjunction with a Chemical Mass Balance (CMB) source-apportionment model, indicated that the spatial variation in the contribution of both mobile and stationary sources to PM2.5 OC often exceeded the variation in OC mass concentration by a factor of 3 or more. Markers for mobile sources, biomass smoke, natural gas, and coal combustion differed by as much as 60% within the neighborhood scale and by greater than 200% within the urban scale. The observations made during this study suggest that the urban excess of carbonaceous aerosols is much more complex than has been previously reported and that a more rigorous, source-oriented approach should be taken in order to assess the risk associated with exposure to carbonaceous aerosols within the industrialized environments of the Midwestern United States. 相似文献
29.
Larson T Gould T Simpson C Liu LJ Claiborn C Lewtas J 《Journal of the Air & Waste Management Association (1995)》2004,54(9):1175-1187
As part of a large exposure assessment and health-effects panel study, 33 trace elements and light-absorbing carbon were measured on 24-hr fixed-site filter samples for particulate matter with an aerodynamic diameter <2.5 microm (PM2.5) collected between September 26, 2000, and May 25, 2001, at a central outdoor site, immediately outside each subject's residence, inside each residence, and on each subject (personal sample). Both two-way (PMF2) and three-way (PMF3) positive matrix factorization were used to deduce the sources contributing to PM2.5. Five sources contributing to the indoor and outdoor samples were identified: vegetative burning, mobile emissions, secondary sulfate, a source rich in chlorine, and a source of crustal-derived material. Vegetative burning contributed more PM2.5 mass on average than any other source in all microenvironments, with average values estimated by PMF2 and PMF3, respectively, of 7.6 and 8.7 microg/m3 for the outdoor samples, 4 and 5.3 microg/m3 for the indoor samples, and 3.8 and 3.4 microg/m3 for the personal samples. Personal exposure to the combustion-related particles was correlated with outdoor sources, whereas exposure to the crustal and chlorine-rich particles was not. Personal exposures to crustal sources were strongly associated with personal activities, especially time spent at school among the child subjects. 相似文献
30.
Arsenault G Lough A Marvin C McAlees A McCrindle R MacInnis G Pleskach K Potter D Riddell N Sverko E Tittlemier S Tomy G 《Chemosphere》2008,72(8):1163-1170
1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) is used primarily as an additive flame retardant. 1H NMR spectroscopy and an X-ray structure determination have revealed that a technical mixture consists largely of two (of the four possible) diastereomers, rac-(1R,2R)-1,2-dibromo-(4S)-4-((1S)-1,2-dibromoethyl)cyclohexane (alpha-TBECH) and rac-(1R,2R)-1,2-dibromo-(4S)-4-((1R)-1,2-dibromoethyl)cyclohexane (beta-TBECH), in a mole ratio of approximately 1:1. The two other possible isomers, gamma- and delta-TBECH, were not detected in a technical mixture. The TBECH isomers are thermally sensitive and can easily interconvert at temperatures of 125 degrees C. A thermal equilibrium mixture of alpha-, beta-, gamma- and delta-TBECH consists of approximately 33%, 33%, 17% and 17% of these isomers, respectively. Separation of all four TBECH diastereomers, with minimal thermal interconversion of the isomers, was achieved by careful selection of GC-capillary column length and injector temperature. Although technical TBECH does not contain the gamma- and delta-isomers, they may still be relevant environmental contaminants since manufacturing processes utilize thermal processes which may induce their formation. 相似文献